Pedestrian traffic signals are presently in widespread use. Most pedestrian traffic signals are of the type which include a rectangular case, and a face plate mounted on the front of the case having a first section bearing the legend "DONT" and a second section bearing the legend "WALK". It is the present practice to replace the words with universally understood symbols. In the neon-type of pedestrian traffic signal, neon tubes are mounted within the case, and the neon tubes are selectively energized. When one of the neon tubes is energized, the command "DONT WALK", or the corresponding symbol, on the face plate is illuminated; when the other of the neon tubes is energized, the word "WALK", or corresponding symbol, is illuminated.
Problems have been encountered in the past in attempts to alleviate the effects of sunlight on the pedestrian signals. When sunlight is reflected from the face plate and interior reflective surface of the signal, it makes it difficult for the pedestrian to understand whether the "WALK" or the "DONT WALK" condition exists.
Visors of different types have been proposed in the past to shade the face of the signal from the effects of sunlight. For example, an egg crate type of visor is described and claimed in U.S. Pat. No. 3,863,251 which issued Jan. 28, 1975 to the present inventors.
However, the prior art visors have not been completely effective in the case of the neon-type signals due to the reflections of sunlight from the reflective surface of the planar rear wall of the prior art signal.
In accordance with the present invention, a pedestrian crossing neon signal is provided in which the housing for the neon lamps is shaped to provide two compartments separated by a divider, with each of the compartments having a parabolic-shaped rear wall and an open front. A neon lamp is positioned in each compartment, and instead of extending across the compartment, the each lamp is positioned at the focal point of the parabolic rear wall of the corresponding compartment, and each neon lamp extends outwardly a short distance from the rear wall of the corresponding compartment.
The result is that when the particular neon lamp is energized, all of its light is directed outwardly through the face plate across the plane of the section of the face plate in front of its compartment so as to illuminate the word or symbol on that section of the face plate to a maximum intensity.
However, when the particular neon lamp is off, any sunlight entering the compartment is reflected by the rear wall to the focal point, and a minimum amount of sunlight is reflected back through the face plate.
Accordingly, the visor now protects the face plate of the signal from external surface reflections, and the reflective rear wall protects the face plate of the signal from internal reflections. The result is that the word or symbol of the illuminated neon lamp is readily visible, even in the presence of sunlight, because of the reflective properties of the parabolic reflective rear wall. However, the word or symbol of the other neon lamp is completely obliterated to all intents and purposes.
The housing of the pedestrian signal of the invention may be constructed of appropriate plastic, such as polycarbonate, or other suitable material, and a highly reflective coating is formed on the inner surface of the housing. This coating, for example, may be aluminum, and it may be formed on the plastic housing by known vacuum deposition processes. Each of the two compartments in the housing, therefore, has a highly reflective surface behind its neon lamp, and the surface in each of the compartments has a parabolic shape. As mentioned above, the neon lamp is mounted at the focal point of the parabolic surface, so that essentially all the light generated by the lamp is directed through the section of face plate in front of the particular compartment.
The section of the face plate covering one of the compartments in the housing is masked with black opaque paint to form the words "DONT WALK", or the corresponding symbol. The section of the face plate covering the other compartment, on the other hand, is masked with black opaque paint to form the words "WALK", or the corresponding symbol.